The Impact of Irregular Sleep-Wake Schedules on Circadian Rhythms and the Role of “Anchor” Sleep

Abstract

In humans the inherent period of the internal oscillator controlling overt circadian rhythmicity is, on average, 25 hr (Wever, 1979). However, when we live under normal nychthemeral circumstances, the internal circadian oscillator is synchronized to a period of exactly 24 hr. The adjustment is achieved by means of rhythmic cues from the external world, for example, the alternation of light and dark, the sleep-wake cycle, social influences, known as Zeitgebers (Aschoff, 1954; Wever, 1979; Minors and Waterhouse, 1981a; Moore-Ede et al., 1982).

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